Visual Illusions Viewed as Stabilized Retinal Images

Pritchard, R. M.

doi:10.1080/17470215808416259

Cited by 70 publications

(32 citation statements)

References 11 publications

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“…Our results directly confirm the hypothesis proposed by Pritchard (15), Mon-Williams and Wann (17), and Zanker and colleagues (18)(19)(20) that small eye movements can drive the perception of illusory motion in Enigma and other static patterns. Thus, our findings are compatible with a causal relationship between microsaccade rates and the perception of illusory motion.…”

Section: Effect Of Microsaccades In the Perception Of Illusory Motionsupporting

confidence: 81%

“…This hypothesis was later supported by Zeki et al (12), who found different sets of cortical areas to be active during the perception of objective vs. illusory motion, and more recently by Kumar and Glaser (13) and Hamburger (14). The third potential explanation of illusory motion in static repetitive patterns came from Pritchard (15), who proposed that the illusion might be due to changes in retinal stimulation produced by small eye movements. This proposal was supported by Evans and Marsden (16), Mon-Williams and Wann (17), and Zanker and colleagues (18)(19)(20), who investigated another op-art painting giving rise to illusory motion effects: Fall, by Bridget Riley (Fig.…”

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confidence: 99%

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Microsaccades drive illusory motion in theEnigmaillusion

Troncoso

Macknik

Otero‐Millan

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

100

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Visual images consisting of repetitive patterns can elicit striking illusory motion percepts. For almost 200 years, artists, psychologists, and neuroscientists have debated whether this type of illusion originates in the eye or in the brain. For more than a decade, the controversy has centered on the powerful illusory motion perceived in the painting Enigma, created by op-artist Isia Leviant. However, no previous study has directly correlated the Enigma illusion to any specific physiological mechanism, and so the debate rages on. Here, we show that microsaccades, a type of miniature eye movement produced during visual fixation, can drive illusory motion in Enigma. We asked subjects to indicate when illusory motion sped up or slowed down during the observation of Enigma while we simultaneously recorded their eye movements with high precision. Before ''faster'' motion periods, the rate of microsaccades increased. Before ''slower/no'' motion periods, the rate of microsaccades decreased. These results reveal a direct link between microsaccade production and the perception of illusory motion in Enigma and rule out the hypothesis that the origin of the illusion is purely cortical.bistable perception ͉ fixational eye movements ͉ miniature eye movements ͉ subjective motion ͉ visual fixation

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Section: Effect Of Microsaccades In the Perception Of Illusory Motionsupporting

confidence: 81%

mentioning

confidence: 99%

Microsaccades drive illusory motion in theEnigmaillusion

Troncoso

Macknik

Otero‐Millan

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

100

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“…The evidence seems to us equivocal, but we tend to favor the hypothesis of mistracking commencing at the intersection of transversal and parallel. Mistracking does not imply mistracking by eye, since such errors still occur under stopped-image conditions in which the proximal stimulus is fixed with respect to the retina (Pritchard, 1958).…”

Section: Overview and Theorymentioning

confidence: 99%

Contour displacements and tracking errors: Probing ’twixt Poggendorff parallels

Tong

Weintraub

1974

Perception & Psychophysics

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Explanations of the Poggendorff effect were tested by varying the separation between outer parallels and by adding interior parallels. Error decreased with the addition of interior parallels, which can be explained by repulsion of parallels. A strong linear trend existed for judgmental error in millimeters plotted against separation between outer parallels. The nonzero intercept of a best-fit line and the slight nonlinearity of the data suggest a hypothesis of contour repulsion between parallels at moderate separations coupled with mistracking of the transversal across the region between parallels. Since the Poggendorff effect was independent of viewing distance, perceptual errors cannot be explained by purely peripheral mechanisms. A true intersection between transversal and parallel was the most critical feature of a display. Inverting a display increased the mean error.The Poggendorff effect occurs when parallel lines interrupt a transversal. Three statements describing why the transversal segments do not appear to be collinear might serve as a focus for research: The parallels appear too close together. Or, transversal segments are rnisperceived in orientation. Or, a tracking error leads to misjudBing the coDinearity of the transversal segments.!he purpose of the series of experiments to be reported IS to examine in detail the role of the parallels and the space between in order to limit the range of admissible hYPOtheses.The display employed was a modified version of the traditional Poggendorff display in which the upper right segment of the transversal was replaced by a dot lying on the right parallel line. The S's task was to set the dot so that it appeared to be collinear with the lower left transversal segment. The modified display is easier to construct, calibrate, and use in experiments employing the method of adjustment. It also precludes the complaints of some observers that the two transversal segments do not even appear to be parallel, and a collinearity setting is therefore impossible. The modified display produces large effects (Weintraub & Krantz, 1971) similar to those obtained with the traditional display.If parallel lines appear perceptually as too close together, then the apparent collinearity of transversal segment and dot would be disturbed in a manner compatible with the Poggendorff effect of setting the dot too low (see Inset A in Fig. 5):Models of contour interaction based upon lateral inhibition normally predict a repulsion between contours that decreases with increasing separation between them (for example, Ganz,

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“…Some early investigators suggested that reversals resulted from changes in eye position (e.g., Necker, cited in Boring, 1942;Titchener, 19(5). However, subsequent research demonstrated that reversals could take place without eye movements (e.g., Pritchard, 1958) and that eye movements may even result from the reversals rather than the other way around (e.g., Flamm & Bergum, 1977;Pheiffer, Eure, & Hamilton, 1956). Another early explanation involved accommodation changes which determined the "near" or "far" side of the Necker cube (e.g., Vicholskovska,19(6).…”

Section: Notesmentioning

confidence: 99%

As the cube turns: Evidence for two processes in the perception of a dynamic reversible figure

Long

Toppino

Kostenbauder

1983

Perception & Psychophysics

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The reported reversals of a rotating Necker cube, which changes direction of rotation when a perspective reversal occurs, were examined under a number of conditions. These permitted comparisons of reversal rates within viewing periods, across successive viewing periods within an experimental session, and across successive weekly sessions. In addition, observers viewed either one or two rotating cubes simultaneously within each of the various viewing periods. Clear evidence for a learning effect was obtained in the form of significant savings across successive viewing periods and sessions. At the same time, results from the multiple-cube conditions and from the pattern of reversals within individual viewing periods appeared to be more consistent with a process of neural fatigue. A two-stage model of reversible-figure perception is proposed which is characterized by (1) fatiguing with extended viewing of the two sets of neural channels that underlie the two percepts of the reversible figure, and (2) learning, which helps to establish the organization of the cortical channels as well as moderate channel activity via such processes as attention and strategy.In the last decade there has been a resurgence of theoretical and empirical activity related to a particular class of visual illusions most commonly referred to as reversible figures. This class of illusions includes such well-known figures as the Necker cube, Rubin's vase-faces, the Schroeder staircase, the Mach folded card, Fisher's man-girl, Boring's young girl-old woman, the Maltese cross, and several others (see Attneave, 1971, for examples of these and other reversible figures). Although empirical research with these figures can be traced back to the last century, there is still extensive interest in them because of the insights they are thought to provide into the nature of the perceptual process by their curious multistable character.Two competing classes of theories have evolved in an attempt to explain the perceptual fluctuations reported for the Necker cube and other reversiblefigure illusions. I The older theory, that of neural satiation (cf. Attneave, 1971;Howard, 1961;Kohler & Wallach, 1944;Orbach, Ehrlich, & Heath, 1963), proposes a passive process of fatigue as the basis for perceived reversals. In this view, the cortical organization underlying one perspective of a reversible figure satiates or fatigues with extended viewing. It then gives way to a second, fresher cortical organization underlying the other perspective. This

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Visual Illusions Viewed as Stabilized Retinal Images

Cited by 70 publications

References 11 publications

Microsaccades drive illusory motion in theEnigmaillusion

Microsaccades drive illusory motion in theEnigmaillusion

Contour displacements and tracking errors: Probing ’twixt Poggendorff parallels

As the cube turns: Evidence for two processes in the perception of a dynamic reversible figure

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